PURPOSE: We assessed the medium-term (3-year) efficacy of transurethral ethanol injection therapy of the prostate (EIP) for benign prostatic hyperplasia. MATERIALS AND METHODS: A total of 34 patients were followed for a median of 4.3 years after EIP. Mean age was 68.1 years and mean baseline prostate volume was 49.3 ml. With the patient under combined sacral and urethral anesthesia, dehydrated ethanol was injected into the prostate with endoscopic guidance. A urethral catheter was inserted postoperatively. RESULTS: Mean total ethanol dose was 6.4 ml and a catheter was required for a mean of 7.6 days postoperatively. Mean International Prostate Symptom Score was 21.8 points before EIP (in 34 patients), and decreased to 13.1 points after 3 years (in 17, p <0.01). Mean quality of life index decreased from 5.0 points before EIP to 2.8 points after 3 years (p <0.001). Mean peak urine flow rate was 8.3 ml per second before EIP and increased to 12.7 ml per second after 3 years (p <0.01). Mean residual urine volume decreased from 93 ml before EIP to 28 ml after 3 years (p <0.01). Mean prostate volume decreased from 49.3 ml before EIP to 45.7 ml after 1 year (p <0.001), but increased to 51.4 ml after 3 years. No major complications were experienced. By 3 years after surgery 59.0% of patients had not required further treatment. CONCLUSIONS: Transurethral EIP caused minimal complications while maintaining improvement of the prostate symptom score and an increased peak urine flow after 3 years.